Atennis player throws a ball vertically upwards at 4.90 m/s. how long, in seconds, does the ball take to return to his hand (assuming it has not moved since releasing the ball)? assume a gravitational acceleration of g = 9.8 m/s^2 and give your answer to 2 decimal places.

If ball return to the hand of player then we can say that displacement of ball will be zero

so here we will have

so here we will have

so it will take 1 second to come back in its hand

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.